As the actors' strike against the advertising industry entered its second week, Screen Actors Guild and American Federation of Television & Radio Artists officials said they have signed more than 150 companies to interim agreements allowing producers to shoot commercials on union terms during the stoppage.

The ad industry has urged advertisers, ad agencies, and commercial production companies not to sign the interim agreements because doing so undermines solidarity in the ongoing labor dispute. But the unions see the defection as a clear sign that they are winning the war-and proof that there is not enough qualified nonunion talent willing to cross picket lines to meet the needs of commercial producers. Twelve years ago, during the previous actors' strike against the ad industry, the unions signed more than 500 companies to interim agreements-a mass defection that helped end the strike after only three weeks.

The unions formed an all-day picket line last Friday in front of the McCann Erickson ad agency in Los Angeles.

The unions also picketed a General Motors commercial shooting Friday night in Encino. The production was marred by an accident that occurred when the car being photographed crashed into a camera suspended from a boom. Nobody was hurt, but the car's windshield "imploded" on impact, according to a striker who witnessed the crash.

Stunt drivers are covered by the unions' commercial contracts, but the operator of the Pontiac Bonneville that crashed Friday was a nonunion employee.

"It points up the need for union drivers on these shoots," strike coordinator Gordon Drake said.

Television commercial production continues nationwide, but not with the help of the Association of Talent Agents, which has asked its members to show solidarity with the unions by not referring talent to commercial producers during the strike. The major talent agencies are reportedly supporting the unions by not sending nonunion talent to auditions, but some smaller agencies are said to be providing talent to struck producers.

"There are probably some small agencies who feel that this is their opportunity now that the major agencies are out of the picture," said a leading talent agent who supports the unions.

Ira Shepard, an attorney for the ad industry, said more talent agencies than the unions think are providing talent during the strike. "There are many talent agencies that are participating with ad agencies and production people in providing talent," he said. "We're being supplied with sufficient union and nonunion talent to be able to produce effectively with qualified talent. We're finding that there is a wealth of qualified talent willing to work-some union and some nonunion. One way or the other, they are willing to work, mostly through agents who are willing to cooperate."

Casting companies are the main source of nonunion talent for struck commercial producers. Strikers distributed leaflets last Friday at seven local casting companies, urging auditioning nonunion actors not to take the jobs of striking actors. Doing so, the leaflets said, could ruin a nonunion performer's chances of becoming a member of either union. Working during a strike is "not your big break," the leaflets said. "It's a big mistake."